Atomic Masses Of First 30 Elements Of The Periodic Table

Atomic Masses Of First 30 Elements Of The Periodic Table

The atomic mass of an element was first determined by John Dalton and Thomas Thomson. However, the discovery of elements did not end with them, and several great scientists embarked on the mission to uncover all the elements found in the world and arranged them in the form of periodic tables.

Atomic mass is the mass of an atom of any given element and is denoted by amu or atomic mass units. Atomic mass is also referred to as molecular weight or atomic weight. Moreover, atomic mass can also be understood as the combination of the total number of protons and neutrons in an element. 

Definition Of Atomic Mass Of Element

The atomic mass of any element is also the total mass or weight of one atom of that particular element. Atomic mass is measured in the atomic mass unit (amu) and is often denoted as u. 

And each unit of atomic mass is defined as “ 1/12 of the mass of a carbon-12 atom in its ground state”. Several definitions of atomic mass were being used before, but this one is the most accurate one.

It is often called relative isotopic mass because every element is different, and thus, the atomic mass is used to donate the average of the masses of all these isotopes. In the periodic table, the atomic masses of every element is determined by their natural isotopes. Carbon 12 nuclide has been used as a standard value to measure the masses of all other elements.

List Of First 30 Elements 

The weight of an individual atom is very small and can only be measured by the mass spectrometer. The mass of the atom of the element gets affected due to the interaction of particles in the nucleus. 

Earlier, elements in the periodic table were arranged in the order of increasing atomic mass. But later,  scientists cleared that it was not the atomic mass, which determines the properties of different elements. Still, it is the atomic number that affects the properties of every element.  Thus, the elements should be arranged in order of atomic number. 

Following is the list of all the elements sorted by atomic mass in the order of their atomic number from 1 to 30, with their properties, symbol and atomic number.


Symbol  Atomic number Name of the element Atomic mass (amu, g/mol) Physical properties
H 1 Hydrogen 1.0079 Colourless, odourless and has low density. 
He 2 Helium 4.0026 It is an Inert gas and has the lowest boiling and melting point. 
Li 3 Lithium  6.941 Lithium has low density and viscosity
Be 4 Beryllium  9.0121 Excellent thermal conductivity and can resist oxidation
B 5 Boron  10.8 Poor conductor of electricity
C 6 Carbon  12.01 Carbon can form a long chain of atoms
N 7 Nitrogen  14.006 Colourless and odourless
0 8 Oxygen  15.999 Colourless, odourless and is paramagnetic
F 9 Fluorine  18.9984 Burns with a bright flame when combined with water.
Ne 10 Neon  20.179 Gives out reddish-orange light when current is passed through it
Na 11 Sodium  22.989 Highly Reactive and soft 
Mg 12 Magnesium  24.30 Burns with glare, hence used in crackers
Al  13 Aluminium  26.981 Light and highly malleable
Si  14 Silicon  28.08 Purely electropositive and brittle
15 Phosphorous  30.973 Exists in different allotropic forms – white, black, and red
16 Sulphur  32.06 Produces a blue flame and strange odour when burnt
Cl  17 Chlorine  35.45 Gives out a suffocating smell and is greenish-yellow in colour
Ar  18 Argon  39.94 Odourless, colourless and inert gas
19 Potassium  39.098 Soft and can float on water
Ca  20 Calcium  40.08 Soft metal, which turns greyish when left in sunlight.
Sc  21 Scandium  44.9 Has a soft texture and burns easily in the air
Ti  22 Titanium  47.90 Exhibits metallic lustre and ductility
23 Vanadium  50.94 Resistant to oxidation
Cr  24 Chromium  51.99 Chromium has a high melting point and has a crystalline structure
Mn  25 Manganese  54.93 Burns in oxygen and can dissolve in dilute acids
Fe  26 Iron  55.84 Gets rusted in the presence of water and oxygen
Co  27 Cobalt  58.93 Lustrous and brittle
Ni  28 Nickel  58.70 Good conductor of heat and electricity
Cu  29 Copper  63.54 Copper is amorphous in its solid state and a good conductor of electricity. 
Zn  30 Zinc  65.38 Zinc is a very sparkly, whitish-blue metal

How To Calculate The Atomic Mass 

The proton and neutron present in an atom determine the mass of an atom. So if you do not know how to calculate the atomic mass of an atom in any element, follow the following steps.

  • Find out the total number of neutrons and protons in that single atom. To find the number of protons, look for the atomic number of the element. 
  • Now add the number of protons to the number of neutrons present in that specific isotope to get its mass number. 

However, many students often get confused between atomic and mass numbers. So, here is a brief comparison of atomic and mass numbers

Comparison Of Atomic Number and Atomic Mass

Atomic Mass Atomic Number
It is the sum of protons and neutrons in an atom. Atomic number signifies the number of proton in an atom
It is denoted by A Atomic number is denoted by Z
Atomic Mass is measured in terms of AMU ( atomic mass unit) It is a number used to arrange the elements in a periodic table and hence are not measurable. 
Atomic mass cannot be used for the identification of elements  Atomic number helps in arranging and grouping elements with similar nature. 


Final Remarks

Atomic mass is the sum of protons and neutrons present in an element. It is denoted by u, which is a symbol of atomic mass unit. According to the standard convention, 1 amu is equivalent to 1/12 the mass of one carbon atom in its ground state. The list above of atomic numbers clearly shows how the difference in atomic number and mass number gives distinct properties to each element. 

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